Technical Abstract:
Three sets of Langdon (LDN) durum-Triticum dicoccoides (LDN-DIC) disomic chromosome substitution lines were previously developed by L. R. Joppa using T. dicoccoides accessions Israel A (IsA), PI 481521 (521), and PI 478742 (742) as the chromosome donors and LDN durum as the recipient. The set based on Israel A was well characterized previously, resulting in the identification and isolation of Gpc-B1, a major gene for high grain protein content (GPC) on chromosome 6B. This study was conducted to identify and characterize genes for high GPC in the two sets based on PI 481521 and PI 478742. The two sets of substitutions lines and controls were grown at Fargo and Prosper, ND, in 2005 and 2006, using a randomized complete block design with four replications. The GPC analysis from the trials showed that the substitution lines LDN(742-6B) and LDN(521-7B) had the highest GPC within their respective sets, suggesting that chromosome 6B of PI 478742 and 7B of PI 481521 carry high GPC genes. In addition, six other substitutions including 1A, 2A, and 5B of PI 481521 and 7A, 5B, and 7B of PI 478742 had significantly higher GPC than LDN. To determine if the GPC gene in PI 478742 is the same as Gpc-B1, we screened three T. dicoccoides accessions and their 6B substitution lines using an allele specific marker Xuhw89 for Gpc-B1. Marker analysis indicated that chromosome 6B of PI 478742 carried the same Gpc-B1 allele as Israel A. A comparison of the chromosomal locations of other GPC genes in the three T. dicoccoides accessions suggested that chromosomes 2A and 7B of PI 481521 and 7A of PI 478742 are likely candidates as sources of new high GPC genes.